Electric control gauge



Sept. l2, 1944.

M. W. CREW ELECTRIC CONTROL GAGE Filed June 26, 1941 IO 24 54 l/BINVENTOR MORRIS W. CREW BY ATTORNE S Patented Sept. 12, 1944 Etnea-nroooN'rnoi. GAUGE:

`Morris W. Crew,A Shaker Heights,y Ohio, assigner to Thel HotstreamHeater Company,

Ohio, a corporat'onof Ohio Cleveland,l

Application; June 2li, 1941', Serial Nio..399',844 Y 6'Cl'ai'ms. (.Cl.2410-56) n 'A This invention relates to improvements in elec-v tricaldraft and pressure control gauges;

An object of' the present invention i`sto provide an instru-mentwhichaccurately indicates a pressure or draft condition and providedwithnrecha'nism which can be r setto control` a predetermined draft orpressure as desired by'meansV o'f electrically Icontrolled apparatus;"Ihe control gauge may be set to hold a predetermined? draft 'orpressure and any variationof the indicateddraft or pressure from thepredetermined setting causes' a change Ain electric circuits connected,

with the gauge so as to retu-rn the controlled apparatus tothepredetermined draft or pressure condition.

Another object of the present invention is to provide in a control'gauge of thetype` described an electric switch adapted to make or-breaka Contact upon the slightest changein the pressure' control device,together with 'means for adjust'- ing the position of the electricswitch relative to the control device so that a predetermined pressureor draft condition may be maintained;

Other objects and-'advantages of the present invention Will be apparentfrom the accompany-A ing drawing and description and theessentialfeatures thereof will Ybe set forth in the claims.

In' the drawing, Fig. 1 is 'a front elevational view oi" my improvedmechanism with the front cover .of the gauge housing removed so as tobetter show the parts; Fig. 2 is a sectional view of the same takenalong the line 2-2 of Fig. 1; while Fig. 3 isla wiring diagram showing atypical use of the gauge.

In the housing or box I is mounted a pressure or draft control chamberII comprising a hollow .base member IIa having its topwall entirely orpartially formed of a exible diaphragm member IIb held in place by a topframe member I I'c. It will be understood that a conduit is connected tothe threaded boss I Id leading to the apparatusv in which a given draftor pressure condition is to be maintained. For instance, I contemplatethat the device here shown in one application may be used to control thedraft in a boiler settingvby varying the position of the draft controldamper by meansV ofen electric motor which 'may' be operated to open orclose the damper 'by means of the electric switches of my improvedgauge, as will be hereinafter more fully explained. Connected to thecentral portion of the diaphragm I'Ilz is a rod I2 extending verticallyup- S'ecuredlto` theltop ofthe housing I0 is an in' verted U'shape.bracket I3* which at its lower end supports' the shaft I4? of anoscill'atable member I5. The4 shaft It is supported in asubstantiallyr'ictionless manner by mounting its pointedI endsk in*v cone cups I6and' IT. TheL membery I5 pis rigidlyl xed onv the shaft. I4` by meansof' the nuts indicated: 'Io' a lateral: arm I5a of this member isconnected the clevis I2a for the pur'- pose of transmitting the movementof' diaphragm [fb to the oscillatable member I'5. An'` upwardlyextendingV boss I'5b of the memberI I5'- carries' a pin i8 adapted tooperate a switch actuator" asy will. later` appear'. Another arm I5'c ofthe member t5 supports an adjustable weight I9. A dial2 pointer: 2'0"is' rigidly secured to the memberv I5 and'. extends' downwardly andforwardlyy in frontoi a dial. 2 I, the scale of which is indicated' diagrammatica-ily at S; Fig. 1T.

Means is provided for accurately counterbal- Y ancing 'the parts movablewith the pointer' 210? ward and having at its ,upper end a clevis I2'afor connection tothe indicating' and control mechanism as will laterappear.

so. that this pointer will accurately indicate the pressure in thechamber YI'I on the dial 2I.` To, this end a counterweight. 22 issupported on a screw extending from the member I5 oppositethe armA I'5a.By adjusting' the counterweight 22 one is able to accuratelycounterbalance the oscillata'ble member |15; the rod'I2 and the dead.

weight, if any, of the diaphragm IIb. Another counterweight 23 isadjustably` mounted on an arm extending vertically upward from themember I5 immediately vback of the boss I5b. Thisv arm and thecounterweight 23' have been omitted from: Fig. 1' to avoid confusion.The member 23 maybe adjusted so as to accurately counterbalance thepointer 20. The arrangement ofV thesev parts is: suchth-at. if it werenot for the weight I9 the pointer 20 would remain in any positionv onthe scale S to which it might be moved. Weight I9 thenv acts asv apendulum tending'to return the. pointer 20 to the left-hand end or zeroend of the scale S when the pressure or draft in the chamber I I is infact zero. Obviously then the. position of the pendulum weight I'9 onthearm I'5c will govern the movement of the pointer 20- over thegraduations of the scale S in response to changes in pressure conditionsin chamber II.

A bracket 24' is oscillatably mounted on a .pivot coaxial with the shaftI4. For this purpose a pivot screw 25 is threaded into the bracket I3aroundthe cone cup screw I6. The bracket 24 has a bearing on a'shoulderof the screw 25.

`Fixed to the bracket are a pair' of switches 26 and 21 having theirJcontrol buttons 26a and 21a' spaced'vapart-on opposite sides of Vand'Vclosely V'adjacent the switch actuator 28. This actuator 'is pivotallymounted on a pin 29 securedin the bracket 24. If necessary orl desirablea roller 54 Y may be aflixed to the upper Wall of the U-shape bracket|3: so as to guide the oscillationk of the` bracket 424|.v Thel lowerend of the actuator 28 l is bifurcatedtoengagethe'pin I8. V

The position of the bracket 24 about its pivot is controlledby a nut 30threaded upon a bar 3I Y which is rotatably mounted in the opposite sidewalls" ofY the housing I and manipulated by a knob 32. A pin 30a. on thenut engages in a slotV on the lower end of the bracket 24. A pointer 33is rigidly fastened to the bracket 24 andv ex:-Y

2,357,877 s j. 'Q 'I i. ,Y 4

If the draft should increase, the pointer will Y move in acounterclockwise "direction or toward the right on the scale S. Thiswill movepin I8 in a counterclockwise direction which will oscillateVthe actuator 28 in a clockwise direction engagin'g the switch button26a so as to close switch 26. Referring to Fig. 3, the circuit will thenbe from the line L1 and binding post 40 through line 46, switch blade45, line 41, `switch `26, lines 52 and 53 to binding post 42, thencethrough the motor winding to binding'4 post 43 and through tion to closethe damper which willdecrease theY draft and cause the return of pointer20 to theV Y tends parallel to the pointer 2O so as to be k.read

` upon the same scale S. In Fig. 1 the pointer 33 Yis set to control thedraft at a point in the mid portion of the scale S and the pointer 20 isset to indicate a neutral position of the Vswitches 26 and 21, i. e.,the device is satised and the control gauge is inoperativeat' themoment- A typical wiring diagram illustrating the use of this vdevice isVshown in Fig. 3. lReferring back `for a moment to Fig. 1, it will beunderstood that the binding Vposts 21h of switch .21 are connected line'5| and binding pt4| back to the line Lz. This will operate the controlmotorin a direcposition of Fig. v1 so as to vopen switch 26 and stop thecontrol motor. Thus. the tendency is at all times to operate the controlmotor upon an increase o r decreaseV of draft from the condition of thepointer'33.

by flexible wires to binding posts, `34 and 35 on a board 36 which issupported on. a suitable bracket 31 mounted on the pressure chamberstructure .I,I. In a like manner the binding posts 2Gb of switch 26 areconnected to the binding posts 38 and 39. Service wires L1 and L2 from asource of electriccurrent'are connected to the binding posts 40'and 4|.The binding posts 42, 43 and 44 are Vconnected to thelelectricalapparatus to Y be controlled. For instance in the application of thedevice to draft control above mentioned, it is l assumedV that the draftdamper would be opened and closed byiaV reversible motor, the commonwire for which is connected to the binding post 43, the wire foroperating the motor in direction to close the damper would be connectedto the post 42, and the wire for operating the motor in direction toopen the damper would be connected to. post44. A switch blade 45:iscontrolled by a button 45a mounted on the front cover I0a ofthehousing I0. Several'contacts'are provided for the'switch'blade, 45 as.indicated in Fig. 3.

Y Theposition of the switchrblade there shown is onVV the Abutton forautomatic control which will `presently be described. Buttons are alsopro- Y vided for maximum or minimurmand an"off Y position'of the switchis shown also. n

Y The operation of my improved device is as follows: With .the parts inthe position Vshown in full lines 'in Fig. 1, if the draftdecreases thepointer 20 will move in a clockwise direction or toward the left on thedial scale S. Thiswill A*cause the pin I8 tomove Vin a clockwisedirecztion which' in turn will `move the actuator 28V in acounterclockwise direction toY press againstthe button 21a so as toclose switch 21. Referring now to Fig.'3,fa circuit is contemplated fromL1 through line 46, switch blade 45, lines 41 and 48,l switch 21, lines49 and 5D to binding post 44, then through the winding ofthe controlmotor back tovbinding post 43 and through line 5| back to theother sideof the'supply line L2. at binding This will operate the control motor ina direction to open the damper and to increase the Vdraft so that thepointer 20 will return toward alinement with the set pointer 33 or tothe position of the parts shown in full line in Fig. 1, whereuponswitchY 21 will open and the'control apparatus will stop. l

indicated by the pointer 33 to return the draft conditions to thatpredeterminedY by the setting By rotating'theknb 32 the nut an can .bemoved to the rightkorleft away from the position of Fig. 1 soas tooscillate the bracket-24 to either \one of thel dot-dash Vpositionspartially. shown toY the left and rightpf the full line position of Fig,Y1. and the actuator along with the bracket so as to set the device tocontrol any draft desired.

It should 'beV understood that the switches Y26 and 21 are preferably ofa character like that.'`

shown in Patent No."1,960,020, granted May 22, 1934, to P. K. -McGalLThese switches Vrequire only an extremely slight movement of the controlbuttons 26a and 21a to cause full operation kof the switches.Furthermore they require very little pressure on the control buttons forthe. opera-v tionv of the switches and therefore practically no loadupon the diaphragm I IbV and the connecting In other words theseswitches are of such y atype that the accuracy of the draft indicating npointer` 2O is vnot affected at 'all for practical ,i

parts.

purposes. vIt will benoted that actuator 28 has a very long leverarmfrom I8 to 29 as compared to the lever arm from 26a or 21a to 29 so thatthe very light pressure necessary to operate the switch: buttonsrequires a still llighter pressure at the point I8. ment of thediaphragm IIb is necessary to cause 1 closure of either of theswitches26 or 21, that tended use. The switches 26 and` 21. are adaptedfor use with the customary line voltages and'V therefore such currentmay be connected at the binding posts 40 and 4I and the device is readyto control any standard motor connected tothe binding posts 42,43 and44. f Y i rPhe description; herein is related to the use oft my devicefor the control of draft, but it is equally usefulfor the control .ofpressurev bya slight change/in the linkage at the point I 2; A suitable.linkage for substitution at this point so vas to This of coursewillfcarry'the switches Furthermore such a slight movec struction andvery simply connected for their'einA adapt the device for pressurecontrol is illustrated and described in my copending application SerialNo. 383,965, filed March 18, 1941.

What I claim is:

1. A control gauge comprising means forming a pressure chamber andhavin-g a flexible diaphragm wall, an oscillatable member, connectingmeans for oscillating-said member responsive to movement of saiddiaphragm wall, means for mounting a pair of switches having operatingbuttons spaced apart, said buttons being disposed in opposedrelationship and directed towards each other, an actuator leverpivotally mounted between said buttons for alternatively operating oneor the other of said switches, said lever having a shorter arm forengaging said buttons, and there being an operative connection between alonger arm of said lever and said oscillatable member.

2. A control gauge comprising means forming a pressure chamber andhaving a flexible diaphragm wall, an oscillatable member, connectingmeans for oscillating said member responsive to movement of saiddiaphragm wall, a dial pointer on said oscillatable member, meanscounterweighting said oscillatable member and connecting means andpointer so that all of these parts are in balance about the axis ofmember oscillation, a pendulum weight for governing oscillation of saidmember as pressure in said chamber varies, switch means fixed relativeto said member, and means for operating said switch means by oscillatingmovement of said member.

3. A control gauge comprising means forming a pressure chamber andhaving a flexible diaphragm wall, a member oscillatable about a pivot,connecting means for oscillatingsaid member responsive to movement ofsaid diaphragm wall, a dial pointer on said oscillatable member, meanscounterweighting said oscillatable member and connecting means andpointer so that all of these parts are in balance about the axis ofmember oscillation, a pendulum weight for governing oscillation of saidmember as pressure in said chamber varies, a bracket mounted foroscillation about a pivot coaxial with said member pivot, two switcheson said bracket having operating buttons r`spaced apart, an actuatorbetween said buttons for alternatively operating one or the other ofsaid switches, an operative connection between said member and saidactuator, and means for holding said bracket in various adjustedpositions about its pivot.

4. A control gauge comprising means forming a pressure chamber andhaving a flexible diaphragm Wall, an oscillatable member, connectingmeans for oscillating said member responsive to movement of saiddiaphragm wall, means for mounting a pair of switches having operatingbuttons spaced apart, said buttons being disposed in opposedrelationship and directed towards each other, said switches beingoperab-le by slight pressure on said buttons, an actuator lever having ashorter arm lying between and closely adjacent said Ibuttons foralternatively operating one or the other of said switches b-y slightmovement of said arm, and said lever having a longer arm operativelyconnected with said oscillatable member.

5. A control gauge comprising means io-rming a pressure chamber andhaving a flexible diaphragm wall, an oscillatable member, connectingmeans for oscillating said member responsive to movement of saiddiaphragm wall, a dial pointer on said oscillatable member, meanscounterweighting said oscillatable member and connecting means-andpointer so that allof these parts are in balance about the axis ofmember oscillation, a pendulum weight for governing oscillation of saidmember as pressure in said chamber varies, means for mounting a pair ofswitches having operating buttons spaced apart, said switches beingoperable by slight pressure on said buttons, an actuator lever having ashorter arm lying between and closely adjacent said buttons foralternatively operating one or the other of said switches by slightmovement of said arm, and said lever having a longer arm operativelyconnected with said oscillatable member.

6. A control gauge comprising means forming a pressure chamber andhaving a flexible diaphragm wall, an oscillatable member, connectingmeans for oscillating said member responsive to movement of saiddiaphragm wall, a dial pointer on said oscillatable member, meanscounterweighting said oscillatable member and connecting means andpointer so that all o-f these parts are in balance about the axis ofmember oscillation, a pendulum weight for governing oscillation of saidmember as` pressure in said chamber varies, means for mounting a pair ofswitches having operating buttons spaced apart, said switches beingoperable by slight pressure on said buttons, an actuator lever having ashorter arm lying between and closely adjacent said buttons foralternatively operating one or the other of said switches by slightmovement of said arm, said lever having a longer arm operativelyconnected with said oscillatable member, said switch mounting meansbeing movable, means for holding said switch mounting means in variousadjusted positions, and means-adjacent said dial pointer for indicatingthe position of said switch mounting means.

MORRIS W. CREW.

